September 2004

Briefs : Test & Measurement
Photodiode-Based, Passive Ultraviolet Dosimeters

Simple, passive instruments have been developed for measuring the exposure of material specimens to vacuum ultraviolet (VUV) radiation from the Sun. Each instrument contains a silicon photodiode and a coulometer. The photocharge generated in the photodiode is stored in the coulometer. The...

Briefs : Test & Measurement
Measuring Radiation Patterns of Reconfigurable Patch Antennas on Wafers

An apparatus and technique have been devised for measuring the radiation pattern of a microwave patch antenna that is one of a number of identical units that have been fabricated in a planar array on a high-resistivity silicon wafer. The apparatus and technique are intended,...

Briefs : Test & Measurement
Hydraulic Apparatus for Mechanical Testing of Nuts

The figure depicts an apparatus for mechanical testing of nuts In the original application for which the apparatus was developed, the nuts are of a frangible type designed for use with pyrotechnic devices in spacecraft applications in which there are requirements for rapid, one-time separations...

Briefs : Medical
Solution Preserves Nucleic Acids in Body-Fluid Specimens

A solution has been formulated to preserve deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) in specimens of blood, saliva, and other bodily fluids. Specimens of this type are collected for diagnostic molecular pathology, which is becoming the method of choice for diagnosis of many...

Briefs : Medical
Oligodeoxynucleotide Probes for Detecting Intact Cells

A rapid, sensitive test using chemiluminescent oligodeoxynucleotide probes has been developed for detecting, identifying, and enumerating intact cells. The test is intended especially for use in detecting and enumerating bacteria and yeasts in potable water.

Briefs : Physical Sciences
Imaging of γ-Irradiated Regions of a Crystal

A holographic technique has been devised for generating a visible display of the effect of exposure of a photorefractive crystal to γ-rays. The technique exploits the space charge that results from trapping of electrons in defects induced by γ-rays.

Briefs : Physical Sciences
Digital Averaging Phasemeter for Heterodyne Interferometry

A digital averaging phasemeter has been built for measuring the difference between the phases of the unknown and reference heterodyne signals in a heterodyne laser interferometer. This phasemeter performs well enough to enable interferometric measurements of distance with accuracy of the...

Briefs : Physical Sciences
Part 2 of a Computational Study of a Drop-Laden Mixing Layer

This second of three reports on a computational study of a mixing layer laden with evaporating liquid drops presents the evaluation of Large Eddy Simulation (LES) models.

Briefs : Physical Sciences
Microwave-Spectral Signatures Would Reveal Concealed Objects

A proposed technique for locating concealed objects (especially small antipersonnel land mines) involves the acquisition and processing of spectral signatures over broad microwave frequency bands. This technique was conceived to overcome the weaknesses of older narrow-band...

Briefs : Mechanical & Fluid Systems
Demonstration of a Pyrotechnic Bolt-Retractor System

A paper describes a demonstration of the X-38 bolt-retractor system (BRS) on a spacecraft-simulating apparatus, called the Large Mobility Base, in NASA Flight Robotics Laboratory (FRL). The BRS design was proven safe by testing in NASA Pyrotechnic Shock Facility (PSF) before being demonstrated...

Briefs : Electronics & Computers
Low-Cutoff, High-Pass Digital Filtering of Neural Signals

The figure depicts the major functional blocks of a system, now undergoing development, for conditioning neural signals acquired by electrodes implanted in a brain. The overall functions to be performed by this system can be summarized as preamplification, multiplexing,digitization, and...

Briefs : Electronics & Computers
Iterative Demodulation and Decoding of Non-Square QAM

It has been shown that a non-square (NS)22n+1-ary (where n is a positive integer) quadrature amplitude modulation [(NS)2 22n+1-QAM] has inherent memory that can be exploited to obtain coding gains. Moreover, it should not be necessary to build new hardware to realize...

Briefs : Information Technology
Further Improvement in 3DGRAPE

"3DGRAPE/AL:V2" denotes version 2 of the Three - Dimensional Grids About Anything by Poisson's Equation with Upgrades from Ames and Langley computer program. The preceding version, 3DGRAPE/AL, was described in "Improved 3DGRAPE" (ARC-14069) NASA Tech Briefs ,Vol.21, No.5 (May 1997), page 66....

Briefs : Information Technology
Ground Support Software for Spaceborne Instrumentation

ION is a system of ground support software for the ion and neutral mass spectrometer (INMS) instrument aboard the Cassini spacecraft. By incorporating commercial off - the - shelf database, Web server, and Java application components, ION offers considerably more ground - support - service...

Briefs : Information Technology
MER SPICE Interface

MER SPICE Interface is a software module for use in conjunction with the Mars Exploration Rover (MER) mission and the SPICE software system of the Navigation and Ancillary Information Facility (NAIF) at NASA's Jet Propulsion Laboratory. (SPICE is used to acquire, record, and disseminate engineering, navigational, and other...

Briefs : Information Technology
Analyzing Contents of a Computer Cache

The Cache Contents Estimator (CCE) is a computer program that provides information on the contents of level-1 cache of a PowerPC computer. The CCE is configurable to enable simulation of any processor in the PowerPC family. The need for CCE arises because the contents of level-1 caches are not available to...

Briefs : Information Technology
Discrepancy Reporting Management System

Discrepancy Reporting Management System (DRMS) is a computer program designed for use in the stations of NASA's Deep Space Network (DSN) to help establish the operational history of equipment items; acquire data on the quality of service provided to DSN customers; enable measurement of service performance;...

Briefs : Information Technology
Simultaneous Product Development Provides a New Approach to Design Collaboration

Product development is becoming increasingly global and as a result, new challenges have emerged,such as coordinating geographically dispersed teams of suppliers and partners. Consequently, the modern enterprise is more similar to a network of interconnected nodes...

Briefs : Materials
Brazing SiC/SiC Composites to Metals

Experiments have shown that active brazing alloys (ABAs) can be used to join SiC/SiC composite materials to metals, with bond strengths sufficient for some structural applications. The SiC/SiC composite coupons used in the experiments were made from polymer-based SiC fiber preforms that were chemical-vapor-...

Briefs : Materials
Composite-Material Tanks With Chemically Resistant Liners

Lightweight composite-material tanks with chemically resistant liners have been developed for storage of chemically reactive and/or unstable fluids — especially hydrogen peroxide. These tanks are similar, in some respects, to the ones described in — Lightweight...

Briefs : Materials
Improved BN Coatings on SiC Fibers in SiC Matrices

Modifications of BN-based coatings that are used as interfacial layers between the fibers and matrices of SiC-fiber/SiC-matrix composite materials have been investigated to improve the thermomechanical properties of these materials. Such interfacial coating layers, which are also known as...

Briefs : Mechanical & Fluid Systems
Simulating Operation of a Planetary Rover

Rover Analysis, Modeling, and Simulations (ROAMS) is a computer program that simulates the operation of a robotic vehicle (rover) engaged in exploration of a remote planet. ROAMS is a rover-specific extension of the DARTS and Dshell programs, described in prior NASA Tech Briefs articles, which afford...

Briefs : Mechanical & Fluid Systems
Silicone-Rubber Microvalves Actuated by Paraffin

Microvalves containing silicone-rubber seals actuated by heating and cooling of paraffin have been proposed for development as integral components of microfluidic systems. In comparison with other microvalves actuated by various means (electrostatic, electro-magnetic, piezoelectric, pneumatic, and...

Briefs : Mechanical & Fluid Systems
Flexible Shields for Protecting Spacecraft Against Debris

A report presents the concept of Flexshield —a class of versatile, light-weight, flexible shields for protecting spacecraft against impacts by small meteors and orbiting debris. The Flexshield concept incorporates elements of, but goes beyond, prior space-craft-shielding concepts,...

Briefs : Mechanical & Fluid Systems
Controllable Curved Mirrors Made From Single-Layer EAP Films

A document proposes that light-weight, deployable, large- aperture, controllable curved mirrors made of reflectively coated thin electroactive-polymer (EAP) films be developed for use in spaceborne microwave and optical systems. In these mirrors, the EAP films would serve as both...

Briefs : Manufacturing & Prototyping
Thermally Conductive Metal-Tube/Carbon-Composite Joints

An improved method of fabricating joints between metal and carbon-fiber-based composite materials in lightweight radiators and heat sinks has been devised. Carbon-fiber-based composite materials have been used in such heat-transfer devices because they offer a combination of high thermal...

Briefs : Photonics/Optics
Discrete Wavelength-Locked External Cavity Laser

A prototype improved external cavity laser (ECL) was demonstrated in the second phase of a continuing effort to develop wavelength-agile lasers for fiber-optic communications and trace-gas-sensing applications. This laser is designed to offer next-generation performance for incorporation into...

Briefs : Photonics/Optics
Optoelectronic Instrument Monitors pH in a Culture Medium

An optoelectronic instrument monitors the pH of an aqueous cell-culture medium in a perfused rotating-wall-vessel bioreactor. The instrument is designed to satisfy the following requirements:

Briefs : Manufacturing & Prototyping
Heat Control via Torque

In a proposed advance in friction stir welding, the torque exerted on the workpiece by the friction stir pin would be measured and controlled in an effort to measure and control the total heat input to the workpiece. The total heat input to the workpiece is an important parameter of any welding process (fusion or...

Briefs : Manufacturing & Prototyping
Setup for Visual Observation of Carbon-Nanotube Arc Process

A simple optical setup has been devised to enable safe viewing of the arc and measurement of the interelectrode gap in a process in which carbon nanotubes are produced in an arc between a catalyst-filled carbon anode and a graphite cathode. This setup can be used for visually guided...

Briefs : Manufacturing & Prototyping
Manufacturing High-Quality Carbon Nanotubes at Lower Cost

A modified electric-arc welding process has been developed for manufacturing high-quality batches of carbon nanotubes at relatively low cost. Unlike in some other processes for making carbon nanotubes, metal catalysts are not used and, consequently, it is not necessary to perform...